In the near future, multimedia applications will in full scale enter the world of cellular communications. To support new services, which will set new demands on the infrastructure for radio communications, a new wireless communication system needs to be developed. Third-generation mobile telecommunication systems are now being determined by the global standardization work conducted by public authorities and the industry.
The role of third generation cellular systems will be to satisfy the needs for immediate access to people and information both in the office environment and globally. Requirements on the third generation cellular systems will range from basic speech services to high speed data services, both circuit switched and packet switched. Services will be symmetric as well as asymmetric and will support applications like Internet browsing and video conferencing. It is expected, that voice still will be a dominating application, so flexibility in bandwidth provision to individual users and high efficiency in bandwidth utilization is essential.
In particular, IMT 2000 (International Mobile Telephony 2000) and UMTS (Universal Mobile Telecommunication System) will open up a new spectrum with a new access method that will further serve to increase the capability of cellular systems. UMTS/IMT-2000 access will coexist with the already existing and evolved GSM access and will support full roaming and handover from one system to another, with service mapping between the two access systems.
Furthermore, packet traffic will increase significantly in the future and a packet switched base network will be required. ATM (Asynchronous Transfer Mode) technology is the coming standard as data traffic bearer and a new ATM Adaptation Layer, AAL2, has been standardized to support delay sensitive speech packets. Therefore, ATM switches have been designed for cost efficient switching as well as for transport in cellular systems. Mobile Switching Centers (MSC) handle preliminary lu interfaces towards Radio Network Controllers (RNC) using AAL2 and AAL5 protocols, and fixed network interfaces towards ISDN (Integrated Services Digital Network) ATM LANs (Local Area Networks) and modems.
The RNCs house a radio network control function such as connection establishment and release, handover power control and radio resource handling functions. Moreover, diversity combining services, used at soft handover, and transcoding functions are also located in the RNCs. Each RNC is built on a generic ATM switch, wherein all devices and a processor of the RNC are connected to the ATM switch. Several BTSs (Base Transceiver Stations) can be connected to the RNC via ATM links.
Furthermore, IWU (Interworking Units) are provided in the mobile network in order to support connection to conventional GSM networks and other fixed circuit switched or packet switched networks.
Thus, in switching network elements, a problem arises that complexity and maintenance of call control applications increases due to the combined use of different versions of the applications in different switching techniques or different network generations.
The WO 9620448 discloses a flexible network platform and call processing system based on a logical model which provides an easy way to handle difficult (e.g. multiparty) situations. The flexible network platform is loosely coupled to a telecommunication network and provides services for subscribers, which services may be addressed by dialed numbers. The services relate to basic functionalities such as tones and the like. The logical resource model in the flexible network platform is composed of sessions, legs, virtual terminals, channels and logical resources, wherein a logical resource is an abstraction of the corresponding physical resource in the network.
Furthermore, the EP 0 765 582 discloses a resource model consisting of three layers, i.e. a network layer, a node layer and a component layer. In particular, the resource model deals with network level resources and not with resources inside a switching network element. Moreover, the resource model is an upper level resource model and does not take into account any service like tones or the like.